Ethylene is an essential plant hormone, critical in various physiological processes. These processes include seed germination, leaf senescence, fruit ripening, and the plant’s response to environmental stressors. Ethylene biosynthesis is tightly regulated by two key enzymes, namely 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxidase (ACO). Initially, the prevailing hypothesis suggested that ACS is the limiting factor in the ethylene biosynthesis pathway. Nevertheless, accumulating evidence from various studies has demonstrated that ACO, under specific circumstances, acts as the rate-limiting enzyme in ethylene production. Under normal developmental processes, ACS and ACO collaborate to maintain balanced ethylene production, ensuring proper plant growth and physiology. However, under abiotic stress conditions, such as drought, salinity, extreme temperatures, or pathogen attack, the regulation of ethylene biosynthesis becomes critical for plants’ survival. This review highlights the structural characteristics and examines the transcriptional, post-transcriptional, and post-translational regulation of ACS and ACO and their role under abiotic stress conditions. Reviews on the role of ethylene signaling in abiotic stress adaptation are available. However, a review delineating the role of ACS and ACO in abiotic stress acclimation is unavailable. Exploring how particular ACS and ACO isoforms contribute to a specific plant’s response to various abiotic stresses and understanding how they are regulated can guide the development of focused strategies. These strategies aim to enhance a plant’s ability to cope with environmental challenges more effectively.

中文翻译：

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乙烯生物合成酶、1-氨基环丙烷-1-羧酸酯 (ACC) 合酶 (ACS) 和 ACC 氧化酶 (ACO)：非生物胁迫耐受性中较少探索的参与者

乙烯是一种重要的植物激素，在各种生理过程中至关重要。这些过程包括种子发芽、叶子衰老、果实成熟以及植物对环境压力的反应。乙烯生物合成受到两种关键酶的严格调控，即1-氨基环丙烷-1-羧酸合酶（ACS）和1-氨基环丙烷-1-羧酸氧化酶（ACO）。最初，普遍的假设认为 ACS 是乙烯生物合成途径的限制因素。然而，各种研究积累的证据表明，在特定情况下，ACO 在乙烯生产中充当限速酶。在正常发育过程中，ACS 和 ACO 合作维持平衡的乙烯生产，确保植物正常生长和生理。然而，在非生物胁迫条件下，例如干旱、盐度、极端温度或病原体攻击，乙烯生物合成的调节对于植物的生存变得至关重要。本综述重点介绍了 ACS 和 ACO 的结构特征，并研究了 ACS 和 ACO 的转录、转录后和翻译后调控及其在非生物胁迫条件下的作用。关于乙烯信号传导在非生物胁迫适应中的作用的评论是可用的。然而，目前尚无关于 ACS 和 ACO 在非生物胁迫驯化中的作用的综述。探索特定的 ACS 和 ACO 同工型如何促进特定植物对各种非生物胁迫的反应并了解它们的调节方式可以指导有针对性的策略的制定。这些策略旨在增强工厂更有效应对环境挑战的能力。